This invention relates to the formation of tablets for the chemical industry and more particularly to a tooling face particularly adapted to form a tablet by minimizing or eliminating excipients.
As one can ascertain, tablets are available widely in both the chemical and pharmaceutical industries. Such tablets, for example, incorporate various chemicals, pharmaceuticals and so on and are utilized for various purposes. Essentially, a major difference between tablets for internal consumption and chemical tablets is that the human body can stand non-toxic and inert fillers and excipients which become contaminants in chemical applications.
For example, in chemical tabletting one may form tablet products for water testing or purification, products for dissolving sanitizers and neutralizers in water and various other chemical products. These products are not intended for internal consumption and essentially are designated as chemically reactive tablets. Preferably these chemical tablets should be free of fillers and excipients which can become contaminants in chemical applications as they can react or otherwise form deleterious and/or contain insoluble substances. Such excipients, which are widely used in the tabletting industry, include starch, cellulose, mineral oil, gums as gum Arabic, polyethylene glycols, sodium stearate, magnesium stearate and other materials which help in the tabletting process.
Essentially, tablets are formed by compressing free flowing powders or granules using conventional tablet presses, such as those manufactured by Vector of Iowa, Stokes of Pennsylvania and so on. Such tablet presses serve to compress the material to form a tablet, the shape of which is determined by the shape of the tooling. The normal excipients used are the above-noted materials which eliminate many problems in regard to the tablet such as the binding of machine parts, sticking, picking, tablet capping and lamination and other interference with machine operation and quality of the tablet.
In any event, one usually adds excipients to provide a reliable and uniform tablet. Such chemicals when contained in tablets as indicated can become contaminants. Hence, in chemical applications there is a severe restraint on the excipients that can be used and often a tablet must be created using no additives but utilizing the powdered chemical formulation by itself.
In order to provide tablets, the prior art has employed standard IPT shapes. Thus normal tablet shapes are described in the Tabletting Specification Manual of the Industrial Pharmaceutical Technology Section (IPT) of the Academy of Pharmaceutical Sciences, American Pharmaceutical Association (1981). That publication describes punch tips or tool faces which are generally designated as shallow concave, standard concave, deep concave, extra deep, modified ball and flat face beveled edge.
Generally, flat faced tablets are often made in a manufacturing process and are called slugs. When one employs the standard IPT shapes, as indicated above, one can experience many problems. Certain of the problems are inherent in that chemical formulations, which are typical in chemical applications, have poor internal flow under pressure and create "capping" and "lamination" problems which are normally overcome by the addition of excipients which are undesirable, as indicated above.
The alternative approach is the so-called flat face or slug, as above indicated. The flat face approach creates a cylinder, in the case of round tablets, having a completely flat top. The flat face therefore has a sharp edge or a right angle that is vulnerable to deformation and chipping that substantially affects the tablet appearance (shop worn) and further effects the tablets integrity and weight and generates particles and powders from tumbling or ejection from the tablet press and from normal attrition in packaging, and other processing techniques and transit.
Hence the next standard alternative is to employ the bevel edge configuration which resembles the flat face tool but has a small angle or bevel at the edge that avoids the sharp square edges of the flat face. The disadvantage is that the angle where the bevel meets the flat portion of the tablet face provides a corner where "sticky" formulations are not removed completely when the tablet is ejected from the tablet presses. Once sticking starts all the following tablets have a deformed or imperfect appearance. The sticking of course is inherent in the fact that "sticky" chemical formulation would cause adhesion to the associated tool or die.
It is therefore an object of the present invention to provide a tooling face which can be employed in a tablet press and manufacture many chemical tablets without the use of excipients.
It is a further object to provide chemical and industrial tablets relatively eliminating excipients by providing a tablet tooling face which has a substantial flat face surrounded by a smooth flange-like peripheral portion of a given radius or curve.